High-speed graphic recorder



May 14, 1929. c. l. HALL 1,713,226

HIGH SPEED GRAPHIC RECORDER Filed Jan. 16, 1925 2 Sheets-Sheet l F'Lg. I.

Inventor Chester- I. H LL by MW HLs Attorne y May 14, 1929. c. I. HALL 1,713,226

HIGH SPEED GRAPHIC RECORDER Filed Jan. 16. 1925 2 Sheets-Sheet 2 Fig.7.

Ihventor Chester- I. HdLL y ijz HLS Attorr y cording wave shapes,

Patented May 14, 1929.

UNITED STATES CHESTER I. HALL, OF FORT WAYNE, INDIANA, ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.'

HIGH-SPEED GRAPHIC RECORDER.

Application filed January 16', 1925. Serial No. 2,908.

My invention relates to recording instruments and in particular to a recording instrument capable of recording phenomena which occur at a rapid rate and which continue over an appreciable interval of time.

Due to the tendency of electric power companies to build larger and larger power stations for the purpose of more economical distribution, the capacity of the main distribution lines have been greatly increased. Also, due to the extensive interconnection of long distribution networks, a line disturbance in one part of the system may be communicated to the whole system, and cause destructive line surges and transients at points very far distant from the place where the original fault occurred. Because of this concentration of power and interconnection of great power systems, the problem of faults has become acute, and the engineers of large power companies have been forced to enter upon a systematic study of these vital power problems. The recording instrument of the present invention was developed to fit the requirements of investigators in the study of such conditions as the rapid current and voltage variation caused by overloads and short circuits over an appreciable period, for example, over a time interval of sufficient duration to record what happens between the occurrence of a fault and the operation of overload relay devices. \Vhere the investigator is interested in rehe may use an ordinary oscillograph; where he is interested in recording the usual variations in current and voltage, he may use an ordinary graphic recorder. The recorder of my invention is designed to fill the gap between these known types of recorders where it is desired to obtain a comprehensive record of such changes as current and voltage over an appreciable interval with sufficient rapidity as to show the maximum values for each half cycle.

In carrying my invention into effect, I employ an oscillograph type instrument, the most important points of novelty of which exist in the form of measuring galvanometer employed and the character of the lightray reflecting system. The type of galvanometer' used may perhaps more appropriately be termed a heav counter torque electric instrument in w ich the moment of inertia has been reduced and the torque increased to a point where it will follow changes in the quantity measured which occur during Z cycle of a 60 cycle circuit, for example. The light ray reflecting system utilizes a secondary point source of light of intense brilliancy provided by focusing light rays upon a small spherical mirror. The invention also includes certain novel automatic recording features to be explained hereinafter.

The features-of my invention which are believed to be novel and patentable will be pointed out in the claims appended hereto. For a better understanding of my invention, reference is made in the following description to the accompanying drawing in which Figs. 1 and 2 represent different views of the light ray reflecting system of my invention; Figs. 3 and 4 show front and rear perspective views of a meter element built in accordance with my invention; Fig. 5 is an assembly plan view of a multiple unit recording device built in accordance with my invention; Fig. 6 is a wiring diagram showing how the recording apparatus is connected to an alternating current transmission line for automatic operation; and Fig. 7 is a typical record obtainable with this recorder.

In Fig. 1, I have represented a primary light source comprising an incandescent electric lamp 10 arranged in a container 11 which is provided with a lens 12 for' collect ing the light rays and concentrating them upon a highly polished sphere 9 used as a reflector. A slot 13 in the top of the tube allows a band of light rays 14 to be reflected from the sperical mirror to the exterior. The light rays 14 are intercepted by a focusing lens 15, the purpose of which is to direct a single beam of light upon a galvanometer mirror 16. The mirror 16 may be an ordinary concave galvanometermirror and is mounted upon the upper end of the shaft 17. The shaft 17 is preferably made of brass or some other resilient non-magnetic material and has its lower end rigidly secured in a. sup ort 18 which positively holds the lower end f f'om twisting. At some. distance, from the support 18, the shaft 17 is provided with a vane 19 of magnetic material and adjacent the vane is a stationary magnetic system 20. One suitable arrangement of this galvanometer or hcavil y damped meter is shown in Figs. 3 and 4 and will be described more in detail. Now, when no current is flowing through the coils of the stationary magnet system, the shaft 17 and mirror 16 will have a given axial position which will be termed the zero recording position and the system will be adjusted so that a light beam is reflccted from the mirror 16 onto a photosensitive. film 21 wrapped upon a rotatable drum 22. The zero recording position of this beam of light will fall upon the zero recording line 23 of the film. The vertical position of the beam 24 reflected from the spherical mirror may be adjusted by adjusting the support 18 about ahorizontal axis 25 by means of the adjusting screw 26. lVhcn a current [lows in the coil or coils of the stationary magnet system 20, the mag netic vane 19 will be attracted, causing the upper end of shaft 17 to twist a very small amount and thereby move the mirror 16 a corresponding small amount.

This movement is illustrated in Fig. which represents a view looking down upon the apparatus shown in Fig. 1, where full lines may be taken to represent the zero recording position of the mirror 16 and the dotted lines a deflected position of the mirror. The movement of the mirror causes the reflected beam of light 24 to change its direction to that represented in dotted lines 24. It will be evident that such a moving system has a very low moment of inertia but very high torque and counter torque; also that the movement is very slight, so slight, as'not to be noticeable to an observer looking at the vane 19. Such a system is capable of giving a deflection of the light beam 24 proportional to the magnitude of the twisting torque produced by the magnet system with sufficient rapidity as to enable the movable member to return to a zero recording position at the end of each half cycle of a 60 cycle current. The deflection for each half cycle is in the same direction and is proportional to the torque produced, which, in the case assumed, is proportional to the current flowing in the coils of the stationary magnet. Now, if the drum 22 be rotated and the apparatus is suitably enclosed to protect the film from other light, we may obtain a record such as is represented in Fig. 1 which shows up the actual value and the variations in current for each half cycle.

A preferred arrangement for a volt meter element is represented in Figs. 3 and 4. This element consists of two coils 20 connected in series with adjustablepoles 26 and a flux return path comprising a frame 27of cold rolled annealed steel. The moving system includes an annealed steel vane 19 mounted in the air gap between the two magnets upon the upper end of a brass rod 17 which, in the construction shown, is .09 in diameter and 3" long. A small concave galvanometer reflecting mirror 16 having a diameter of is carried by a stiff aluminum holder 28 rigidly secured to the vane 19. The small brass rod or shaft 17 is clamped at the bottom at 29 in such a position that the vane 19 makes an angle of about 45 degrees with the axis of the magnet poles. The vane has an air gap of approximately on each side when in the zero deflecting position and has a deflection of approximately 1 35' for 1 deflection of the recording beam on the film and 110 volts on the coils. The restraining torque of the brass rod is sutlicient to give the moving system a natural frequency of about 600 vibrations per second. The still mirror support is preferably pivoted at the top at 30 to prevent shaft whipping with resultant loops on the film record. The moving element is preferably pivoted about a horizontal axis 25 to the base plate 31 so that its vertical position may be adjusted by means of the thumb screw 32 acting against a spring 32. In describing this structure, I have given specific data for the purpose of illustrating one practical arrangement. However, I do not wish to be limited to these details of construction or to a voltmeter element. Where the current, frequency, power factor or other quantity is to be recorded, the meter coils and construction willbe altered accordingly to give a deflection proportional to such quantities.

The assembly of the recording device is shown in Fig. 5 where I have represented four meter elements at 33, 34, 35 and 36 mounted so as to be supplied from a single light source in the tube 11. The adjustable focusing lenses are represented at 15. The various circuits are carried to a suitable terminal board 37 with external connections.

In accordance with usual practice, the light ray reflecting system is contained in a light tight box 38, the cover of which is removed to show the interior arrangement. In the wall of the box opposite to the meter elements is a slit 39 adjacent to which may be mounted an ordinary film holder 40 containing the revolving drum 22 for holding a photographic film. The film holder is provided with a slit 41 which coincides with slit 39 when the holder is in place. The film holder is removable and when removed, the usual ground glass test plate may be placed over the slit to inspect the light beams for adjusting purposes. At one endof the film holder is a spring motor 42 geared to a crank shaft 43 on which is short mounted a crank 44 cooperating with a crank 45 on the -ad'acent end of the rotatable film holder 22. The spring motor isprovided with a' suitable speed governor such that when the device 1s released, it drives the film holder at the desired speed.

As will be explained in connection with Fig. 6, the motor 42 may be arranged to be released automatically in response to a transient condition on the alternating current system under investigation.

Where automatic operation is desired, a wiring system shown inv Fig. 6 may be employed. In this figure, 50 represents a polyphase alternating current distribution system to which my improved recording apparatus'is connected for automatic operation. An ammeter element 33 is permanently connected to the secondary of a current transformer 51 and a voltmeter element 34 is connected to the secondary of a potential transformer 52 through normally open switch contacts 53. A high speed relay 54 is pro- VldGd and its energizing coil is connected across a shunt 55 in the ammeter circuit. The relay has a plunger of low inertia 56 to the upper end of which is secured. the contact closingmembers 57. The plunger 56 isprovided with a locking device represented as a pivoted lever 58 hinged at one end to the plunger and cooperating at the other end with a latch 59. When the plunger is raised the free end of lever 58 passes below the spring latch 59 so that the contacts closed bythe relay are held closed during the recording period. The relay also closes contacts 60 which energize the primary light source 10 from a battery 61 and contacts 66 in the circuit of a release relay 62 for the spring motor 42, which circuit is energized from a suitable direct current source 63. A lock latch 64 is normally held in engagement with a gear 65 of the film driving motor when relay 62 is deenergized, but as-soon as contacts 66 are closed, relay 62 is energized and attracts its armature, which is secured tothe locking latch 64, to unlock the spring motor drive. The latch 59 is also provided with an unlocking relay 67, the circuitof which iscontrolled by contacts 68 and the crank 44 of the motor drive. The arrange ment is such that after the spring motor is started by the operation of relay 62, it will operate at constant speed so as to rotate the film holder substantially one revolution in about 11 seconds or at such other rate as is desired. At the end of the time for which the motor is set to run, the crank 44 will close contacts 68 which energizes an alarm 69 and the unlocking relay 67 of the high speed relay. When relay 67 is energized, the upper end of the spring catch lever 59 circuits the energizing coil of the high speed relay 54 and element 33 through con tacts 70. Consequently, plunger 56 will drop and open the contacts 53, 60 and 66. Latch 64 again lo'cks the springmotor but alarm 69 and relay 67 remain energized until the motor drive is reset by hand for another operation.

The shunt 55 will be selected so that normal current conditions will not be suflicient to operate relay 54. small deflections of meter element 33 due to the normal current flowing in the system 50, such deflections will not be recorded since, under normal conditions, light source 10 is not energized nor is the film in motion.

To set the apparatus for automatic operation, the film holder will, of course, be loaded with a fresh film. The light ray system will be properly adjusted to bring in proper position on the-film-and for this purpose a switch the light source other parts of the device. During such adjustment, the film holder will be removed and any suitable testing screen will be placed over the slit- 39 where the position of the light rays may be observed from the outside. When these adjustments are made, the spring motor 42 will be wound up and locked with the crank 44 in engagement with crank 45 and with the film holder positioned at the startingpoint, contacts 68 being open, and with the various relays positioned as represented in in this 'condition'indefinitely and until a short circuit or other heavy overload occurs. As soon as a rush of current sufli'cient to 0perate the high speed relay occurs, this relay will operate. It is especially designed with a very low inertia plunger so that its operation and the closing of the various circuits will take place almost instantaneously after the predetermined overload occurs. The operation of the relay energizes the voltmeter element 34, light source 10 and relay 62. The film motor is unlocked and the recording operation is started. The plunger 56 of the high speed relay is locked up by latch 59 so that even though the line current drops to zero or to a normal value, the recording operation will go on for an appreciable period of time, for example, 15 seconds, so that the record will show the complete changes which took place from the beginning of the trouble until normal conditions have again been established or the line opened by the operation of overload circuit breakers.

At the end of the recording period, contacts 68 are closed, the plunger 56 of the high speed relay is released, contacts 53, 60 and 66 opened, thereby opening the circuits of voltmeter element 34, light source 10 and locking relay 62. The film is stopped by the locking of its driving mechanism, alarm 69 operates, and the coil of relay 54 is short circuited so that another operation is prevented until the device is reset.

the light beams.

71 is provided to energize 10 without disturbing the Fig. 6. The apparatus may be left While there may be It will generally be desirable to rovide meter recording elements in each p ase of i, the polyphase circuit but for the sake of simplicity, only one current element and one voltage element is represented in Fig. 6.

Fig. 7 represents the type of record obtainable with this apparatus. Curve arepresents a current record and curve I) represents a corresponding voltage record for a circuit connection such as is represented in Fig. 6 where the current recorded is due to a variable resistance connected across the phases measured by the voltmeter element. In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means. What I claim as new and desire to secure by Letters Patent of the United States is 1. Apparatus for recording phenomena of an electric circuit comprising a reflection galvanometer connected to be influenced by said circuit, a photographic film, a llght ray reflecting system for tracing the movements of said' reflection, galvanometer upon said film, a light source for said system, a motor for moving said film, means for starting said motor, a relay for simultaneously energizing said light source and controlling said motor starting means, connections for energizing said relay upon the occurrence of an abnormal condition of said circuit, and

means for maintaining said relay in its energized position for a predetermined time after its operation.

2. Apparatus for recording phenomena of an electric circuit comprising a reflection galvanometer connected to be influenced by said circuit, a photographic film, a light ray reflecting system for tracing the movements of said galvanometer upon said film, a light source for said system, a motor for moving vsaid film, means for starting said motor, a

relay for simultaneously energizing said light source and controlling said motor starting means to start the motor, connections for operatively energizing said relay upon the occurrence of an abnormal condition of said circuit, and means for maintaining said relay in its energized position 'for a predetermined time after its operation and thereafter deenergizing its circuit and the circuit of the galvanometer.

3. Apparatus for recording phenomena of an electric circuit comprising a reflection galvanometer connected to be influenced by the current of said circuit, a normally disconnected reflection galva'nometer arranged when energized to be influenced by the potential of said circuit, a photographic film,

a light ray reflecting system for tracing the movements of said galvanometer upon said film, a light source for said system, a motor for moving said film, means for starting said motor a relay for simultaneous] energizing said light source, said potentia galvanometer and controlling said motor starting means, connections for operatively energizing said relay upon the occurrence of an abnormal current in said circuit, and means for maintaining said relay in its energized position for a predetermined time after its operation.

4. In an apparatusfor recording the phenomena of an electric circuit, a galvanometer comprising a mirror mounted on one end of a torsion shaft, the other end of said shaft being secured in a fixed position, an armatune on said shaft, a field member operatively related to said armature provided with a winding adapted to be connected to the circuit under investigation, a light ray system arranged to reflect a beam of light from the mirror mounted at the end of the torsion shaft onto a recording film, and

means for starting the film in operation a light ray reflecting system for tracing the movements of said reflecting galvanometer upon sa1d film, a light source for sa1d system, a motor for producing relative move- -ment between said film and the recording light my in a direction substantially at right angles to the recording movement of such ray as produced by movements of the galvanometer, means for starting said motor, a relay for simultaneously energizing said light source and controlling said motor starting means, connections for energizing said relay upon theoccurrence of an abnormal condition of the circuit, and means for maintaining said relay in its energized position for a predetermined time after its operation.

,6. In-combination with an electric circuit, a galvanometer connected to be influenced by such circuit, a normally inactive light ray recording system for photographically reproducing the movements of said galvanometer, means responsive to an abnormal condition of said circuit for setting said recordmg systeminto operation, and means for maintaining it in operation for a predetermined length of time thereafter and then rendering it inactive until-the occurrence of another abnormal condition.

,7. In combination with an electric circuit,

a galvanometer connected to be influenced,

normally inactive light my reeording system for photographieaily reproducing the movements of said galvanometers, means responsive to the oecurrenee of an abnormal current condition of said circuit for setting said recording system into operation and simultaneously energizing the second men tioned g'alvanometer, and means for rendering said recording system and second mentioned galvanometer inactive after a predetermined interval.

In Witness whereof, I have hereunto set my hand this 12th day 0i January, 1925.

CHESTER I. HALL. 

